To monitor the current state of supply networks, such as spatially extensive supply networks for flowing media such as supply water, gas, or oil, a multiplicity of measuring devices can be provided which are installed at precisely defined positions in order to measure, and convey to a control station, current measurement values such as, for example, the pressure, the flow or the rate of flow.
The control station can be a central or decentralized control room including appropriate devices, from which control room the supply network is managed, that is to say that the monitoring and controlling of the operation of the network is carried out from here. In the control room, the measurement signals and measurement values conveyed are correspondingly processed further and visually displayed.
Due to the frequently large spatial extension of supply networks, the data transmission of the many sensors is frequently not provided by cable but by radio to the control station. This dispenses with laying and maintaining expensive cable installations along the supply lines.
The measurement values determined in each case by the sensors are transmitted by radio, for example by means of GPRS (General Packet Radio Service) to a compatible receiver which then forwards these to the control station.
The power supply for the measuring devices and transmitting and receiving devices is generally provided locally by battery or by supply from energy gained in the environment of the sensor, for example solar current.
To save energy, the individual data items to be transmitted are combined and/or processed further in data packets, for example mean values are formed, compressed and transmitted by radio, at fixed times, for example every 30 minutes.
However, this has the disadvantage that current information about the network status is available only at particular times and in the case of problems in the network, a delay occurs in the transmission of information.
On the other hand, an inappropriate increase in the frequency of data transmission in the case of sensors operated purely by battery would lead to the battery capacity being exhausted earlier and the batteries, therefore, having to be replaced more frequently, such that a part of the maintenance workers would only be used for this purpose and could not be used for other maintenance measures. The resultant additional expenditure on personnel or time delays in performing such measures represent a considerable cost factor.
Another aspect which plays a role in this connection and should be taken into consideration relates to the abundance of sensors used. While the abundance, and thus the distribution of sensors, is limited because of the purchasing and maintenance costs at that time, in numerous known supply systems, for example, for a relatively long time, significantly more sensors can be found in more recent installed systems, in less large spatially extensive supply systems because of the recently comparatively low costs for purchasing and operating sensor systems. It is this circumstance which has led to more and more sensor systems being used in the field.
The volumes of data transmitted into the control station in this context are very large, on the one hand, but, on the other hand, also frequently of poor quality, with the consequence that the data cannot be used for analysis purposes, or only in a very restricted way.